Many communication protocols include a preamble at the start of each data frame to be used for synchronization and channel equalization at the receiver. The preamble often consists of repeated patterns, one pattern for the synchronization section and a different pattern for the channel equalization section of the preamble, with each pattern designed for their respective functions. The purpose of the frame synchronization function within a receiver is to establish a specific boundary within the frame, such as the beginning of the channel equalization symbols, the beginning of the header, or the beginning of the user data. Typically, frame synchronization is established using some feature of the synchronization patterns. For example, the WiMedia Alliance physical layer standard for ultra wideband communications prescribes a repeated synchronization pattern where the repetitions are sometimes inverted based upon position within the preamble. The particular pattern of inverted and non-inverted symbols can then be used to establish the end of the synchronization patterns and thus achieve frame synchronization.
One drawback to this type of frame synchronization method that relies on phase changes during the synchronization portion of the preamble is that it is vulnerable to extraneous phase changes. These might be caused, for example, by perturbations within the analog portion of the transceiver.
Accordingly a new system and method are needed for frame synchronization.